Press Shop
00635_B.jpg (21339 bytes) Cutting out and protecting

Audi is the only volume manufacturer of automobiles in the world that has decided to manufacture its bodies entirely from sheet metal galvanized on both sides. The extra effort pays off in two different ways: the body retains its strength for much longer, and the car's safety is enhanced - for a longer period too.

Working at high pressure

The body elements are shaped from blanks of various sizes. The first pass through the press determines the general three-dimensional outline. The following stages involve further shaping, stamping out cutouts if necessary and folding the flanged edges.

The maximum pressure exerted by the giant presses is 1,600 metric tons - equivalent to the weight of about 1,300 Audi A4 cars stacked one on top of the other, with a total height of 1.8 kilometers. Sheet metal between 0.6 and 4 millimeters in thickness is reshaped almost as if it were chewing gum, and pressed into the narrow gap between the upper die and the lower matrix of the press tool. The floor pan is subjected to particularly drastic reshaping. Shortly before the sheet metal achieves its final form, a most unusual and unmistakable noise is heard as the metal stretches and is "drawn." It's awe-inspiring evidence of the monumental forces at work here.

Sheet metal is mostly delivered in the form of coils. These can weigh up to 30 tons each. Electronically controlled strip cutters divide the continuous coils up into blanks with the initial dimensions of the elements that will later be formed in the press. Even the trimmed edges remain protected: the blanks are automatically given protective zinc coating after cutting.

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00637_B.jpg (16429 bytes) Giants of precision

Despite their size and a total weight often in the region of 40 tons, the press tools operate attolerances as low as a few hundredths of a millimeter. A single hair would show up as a visible flaw on every body element. The operators therefore inspect every component regularly and examine the finished surfaces for blemishes.

Standing up to pressure

Not many people are to be seen in the press shop, thanks to arduous work of bringing up and removing the metal blanks and pressings having largely been mechanized. A highly qualified specialist team, however, looks after every press line. Electricians, mechanics, toolmakers and logistics experts monitor and control "their" press line and ensurethat high standards of availability and production quality are maintained.

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00640_B.jpg (13561 bytes) Parts made to measure

All the pressings that emerge from this line are produced according to data originating in the design department. The dimensions are determined directly by a robot sensor, and compared with the designers' original CAD (computer-aided design) data. The entire production sequence is geared to the maintenance of consistent high quality. The standards of precision reached by Audi pressings must be confirmed by each successive measurement. If significant tolerance deviations are detected, a report goes instantly to the press-line team so that the cause can be traced and eliminated.

The fully galvanized body - a safety factor too

The zinc coating applied to all the sheet-metal body elements in an Audi prolongs the pleasure of owning a fine car, since it retains its appearance and incidentally its value for a much longer period. Zinc corrodes between five and ten times more slowly than ferrous metals. Even if a panel is scratched and the steel surface exposed, the zinc at this point is 'consumed' first before the sheet steel begins to suffer. This also has beneficial effects on the safety standard of the Audi automobile. The strength of the occupant zone and the programmed crumple effect that ensures crash protection are maintained reliably for many years. All current Audi models carry a ten-year warranty against body penetration by rust. About five kiograms of zinc can protect an entire Audi bodyshell.

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zinc.jpg (8134 bytes) Steel recycles well

All Audi automobiles are designed for long life, which in itself helps to protect the world's dwindling raw-material resources. But Audi achieves the same goal by other means too: in the press shop, for instance, almost all the metal scrap and offcuts are re-used, for instance to make small parts wherever possible. Material that Audi cannot re-use is compressed into bales and returned to the steelworks, where steel and zinc are separated so that they can be reprocessed. Another by no means self-evident principle that Audi has none the less adopted: the press shop utilizes vegetable-based lubricating oils and hydraulic fluids wherever possible.

Production


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